Everyone has genetic code stored in 23 pairs of chromosomes per cell; half come from the mother and half from the father. Down syndrome is caused by a mutation of chromosome 21 resulting in an individual having a partial or extra copy of the chromosome. There are three different types of Down syndrome: trisomy 21(nondisjunction), mosaicism and translocation. Nondisjunction accounts for approximately 95% of DS cases and is caused by an additional chromosome added to the pair on chromosome 21. When chromosome 21 splits and attaches itself to another chromosome, this is called translocation. Nearly 4% of Down syndrome cases are due to translocation. Mosaicism happens when a mutation of chromosome 21 occurs in one but not all cells, and this accounts for about 1% of Down syndrome cases.
The Cause of Down Syndrome
The cause of Down syndrome is unknown, but some research has pointed to the father's genes playing a role. Research does not support environmental factors or the parents' lifestyle during or after the pregnancy as a cause, however it has shown that the chances of having a baby with Down syndrome increase with the mother's age. On the other hand, 80% of babies born with Down syndrome are born to women under the age of 35 due to higher fertility rates in younger women.
Down Syndrome Tendencies
Individuals with Down syndrome can usually be recognized by their appearance. They tend to have a small build, slanted eyes and one crease in their palms, though these traits can vary from one person to the next. Cognitive delays are common, but they are usually mild to moderate. Their condition generally does not stop them from enjoying many of the things in which typical people participate. They go to school and work, and some even become actors, singers and swimmers. Lauren Potter is an actress with Down syndrome who plays Becky Jackson in the popular TV show, Glee. As you can tell, they can be very talented individuals who are special beyond the traditional meaning of the word.
As you go through the month of October, keep people with Down syndrome in mind. Spread the word about it and help raise money for further research. Find a Buddy Walk® in your city, http://www.ndss.org/Buddy-Walk/Find-a-Buddy-Walk/. If you are close to someone with Down syndrome, give them a hug and let them know how much they mean to you.
http://www.ndss.org (National Down Syndrome Society)
http://www.ninds.nih.gov (National Institute of Neurological Disorders and Stroke)
http://www.ncbi.nlm.nih.gov (Pub Med Health)